#include <bits/stdc++.h>
using namespace std;

inline int read() {
	int x = 0, f = 0; char ch = getchar();
	while (ch < '0' or ch > '9') f |= (ch == '-'), ch = getchar();
	while (ch >= '0' and ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
	return f ? -x : x;
}

int __stk[128], __top;
inline void write(int x) {
    if(x < 0) putchar('-'), x = -x;
	do { __stk[++__top] = x % 10, x /= 10; } while (x);
	while (__top) putchar(__stk[__top--] + '0');
}

const int mod = 998244353;

void Min(int &x, int y) { y < x and (x = y); }
void Max(int &x, int y) { y > x and (x = y); }

void inc(int &x, int y) { (x += y) >= mod and (x -= mod); }
void mul(int &x, int y) { x = 1ll * x * y % mod; }

int q_pow(int x, int k) { int res = 1; for (; k; k >>= 1, mul(x, x)) if (k & 1) mul(res, x); return res; }

bool stmer;

const int N = 1e5 + 10, M = 20;

int n, m, q;
int dep[N], fa[N];

bool Ans[N];

vector<int> e[N];

namespace ST {
    int cnt;
    int dfn[N], rnk[N], st[M][N], lg[N];

    int get(int x, int y) { return dep[x] < dep[y] ? x : y; }
        
    void dfs(int x) {
        dep[x] = dep[fa[x]] + 1, rnk[dfn[x] = ++cnt] = x;
        for (int v : e[x]) if (v ^ fa[x]) fa[v] = x, dfs(v);
    }

    int ask(int l, int r) {
        l = dfn[l], r = dfn[r]; if (l > r) swap(l, r); 
        if (l++ == r) return rnk[r]; int h = lg[r - l + 1];
        return fa[get(st[h][l], st[h][r - (1 << h) + 1])];
    }

    int dis(int x, int y) {
        return dep[x] + dep[y] - 2 * dep[ask(x, y)];
    }

    void init() {
        lg[0] = -1, dfs(1);
        for (int i = 1; i <= n; i++) st[0][i] = rnk[i], lg[i] = lg[i >> 1] + 1;
        for (int i = 1; i <= lg[n]; i++) for (int j = 1; j + (i << 1) - 1 <= n; j++)
            st[i][j] = get(st[i - 1][j], st[i - 1][j + (1 << i - 1)]);
    }
}


struct Ask {
    int x, y, p;
} op[N];

struct node {
    int x, d;
} a[N];

namespace sol {
    const int M = 1010;

    vector<int> e[N], E[N];
    bitset<M> to[M];

    int top, cnt, tot;
    int dfn[N], low[N], stk[N], col[N];

    bool vis[N];
    
    void add(int u, int v) { e[u].push_back(v); }

    void tarjan(int x) {
        dfn[x] = low[x] = ++cnt, stk[++top] = x, vis[x] = 1;
        for (int v : e[x]) {
            if (!dfn[v]) tarjan(v), Min(low[x], low[v]);
            else if (vis[v]) Min(low[x], dfn[v]);
        }
        if (low[x] == dfn[x]) { 
            tot++;
            while (stk[top + 1] ^ x) col[stk[top]] = tot, to[tot][stk[top]] = 1, vis[stk[top--]] = 0;
        }
    }

    void init() {
        for (int i = 1; i <= m; i++) for (int j = 1; j <= m; j++)
            if (i != j and ST :: dis(a[i].x, a[j].x) <= a[i].d) add(i, j);
        
        for (int i = 1; i <= m; i++) if (!dfn[i]) tarjan(i);
        for (int i = 1; i <= m; i++) for (int v : e[i])
            if (col[v] ^ col[i]) E[col[i]].push_back(col[v]);
        
        for (int i = 1; i <= tot; i++) for (int v : E[i]) to[i] |= to[v];
    }

    bool tag[N];

    bool query(int x, int y, int p) {
        if (ST :: dis(x, y) <= p) return 1;
        for (int i = 1; i <= tot; i++) tag[i] = 0;
        for (int i = 1; i <= m; i++) tag[col[i]] |= ST :: dis(x, a[i].x) <= p;
        for (int i = 1; i <= m; i++) if (tag[col[i]] and ST :: dis(a[i].x, y) <= a[i].d) return 1;
        return 0;
    }
}

bool edmer;
signed main() {
	freopen("shu.in", "r", stdin);
	freopen("shu.out", "w", stdout);
	cerr << "[Memory] " << (&stmer - &edmer) / 1024 / 1024 << " MB\n";
	
    n = read(), m = read(), q = read();
    for (int i = 1; i < n; i++) {
        int u = read(), v = read();
        e[u].push_back(v), e[v].push_back(u);
    }

    ST :: init();

    for (int i = 1; i <= q; i++) op[i] = { read(), read(), read() };
    for (int i = 1; i <= m; i++) a[i] = { read(), read() };

    sol :: init();
    for (int i = 1; i <= q; i++) Ans[i] = sol :: query(op[i].x, op[i].y, op[i].p);

    for (int i = 1; i <= q; i++) puts(Ans[i] ? "YES" : "NO");

    cerr << "[Runtime] " << (double) clock() / CLOCKS_PER_SEC << " seconds\n";
	return 0;
} 